Technical Field
The present invention relates to a method of forming a topping sheet and an apparatus thereof.
Related Art
For forming carcass ply that makes a skeleton of a pneumatic tire, first, a textile original fabric, obtained by weaving longitudinally aligned tire cords into a cord fabric by use of weft yarns, is prepared and then topped with unvulcanized rubber to form a topping sheet. Subsequently, the topping sheet is cut off into a length corresponding to a width of the carcass ply to form strip-shaped ply pieces. Further, non-cut ends of the ply pieces are sequentially connected to form a long ply original fabric. Then, the ply original fabric is wound around a molding drum to be expanded outer-diametrically and molded by vulcanization in a tire vulcanizing mold, thereby forming carcass ply.
Each carcass ply has a different width depending on the size and specification of the pneumatic tire, and the ply original fabric is formed for each carcass ply. For this reason, the ply original fabric is once stored in a wound state as an intermediate molded article (intermediate work-in-process) and is then released and supplied at the time of molding the corresponding pneumatic tire. This results in complex production control on the ply original fabric. In order to facilitate the production control on the ply original fabric, it has been proposed that the ply original fabric be directly supplied to a molding step without being stored as the intermediate molded article (e.g., WO2007/007405A1).
The direct supply of the ply original fabric to the molding step requires a compact configuration of an apparatus for forming the ply original fabric because of constraint on equipment arrangement space. For this reason, the topping sheet has been configured to have a width as narrow as about 0.5 m, for example.
However, the topping sheet is typically formed of a wide textile original fabric having a width of about 1.4 m to 1.5 m. That is, a narrow topping sheet has been formed by first topping a wide textile original fabric with the unvulcanized rubber to form a wide topping sheet, and then dividing this sheet widthwise. Another method has also been proposed where tire cords are supplied from a large number of cord bobbins to form a narrow cord original fabric, and this is topped with the unvulcanized rubber to form a narrow topping sheet (e.g., JP 2012-161969 A).